Vehicle service lifts are well-known apparata used to lift vehicles to allow access to their undersides for service purposes. Many vehicle owners own vehicle jacks which allow one side of a vehicle to be lifted to allow changing of tires or other maintenance functions. In professional service shops, vehicle lifts are generally significantly larger and provide tracks whereupon the wheels of a vehicle may be placed. The tracks (and the entire vehicle) are then lifted so that the underside of the vehicle is accessible to service personnel. The vehicle is lifted to such a height that service personnel may operate on the underside of the vehicle with comfort and convenience. An example of such a vehicle lift may be found in U.S. Pat. No. 4,724,930 to VanLierop. Such vehicle lifts are generally quite expensive, and while models can be constructed which accommodate a wide variety of different types and sizes of vehicles, it is impractically expensive to construct service lifts which can accommodate every conceivable vehicle size and weight. As an example, some dual-use vehicles (i.e., all-terrain vehicles which are intended for both off-road and on-road use, such as the HUMMER or HUMVEE manufactured by AM General Corporation) have wheelbases which are significantly larger than standard vehicles, and these cannot be accommodated by any known vehicle lift. As another example, semi tractors are often too large and heavy to allow the use of a vehicle lift. Vehicles such as these are generally serviced by use of a service pit.
A service pit is a pit in a service area floor which is sized so that a vehicle can drive over the pit with the vehicle's wheelbase spanning the pit. Service personnel located in the pit and beneath the underside of the vehicle may reach up to operate on the underside of the vehicle. Service pits are often formed by forming a hole in the service area floor extending to the basement, and reinforcing the surrounding basement ceiling. In this case, since the basement floor may be eight or more feet beneath the underside of vehicles parked over the service pits, a raised platform may be provided on the basement floor beneath the service pit to allow service personnel to more easily reach the undersides of the vehicles. Service pits are advantageous in that they are low in cost and maintenance compared to vehicle lifts, and they can be made with a length sufficient to traverse not only a semi tractor, but an attached trailer as well.
However, service pits are often not viewed as favorably as vehicle lifts by government agencies dealing with workplace safety (e.g., the Occupational Safety and Health Administration, or OSHA), by insurance companies, and even by service shop operators since they present a greater likelihood for accident. It can be disastrous if a vehicle is improperly driven over the service pit and one or more wheels happen to fall into the service pit. Additionally, an open service pit poses a falling hazard for distracted or inattentive service personnel who are walking about the service area. This is particularly true since the service area is often noisy and the service personnel may be wearing welding gear, carrying equipment, or engaging in other activities which may decrease visibility or attentiveness.
Service pits also pose a problem in that their floors may not be optimally spaced from the undersides of vehicles parked thereover. Since the ground clearances of different vehicles can vary radically--from a foot or so for sports cars to several feet for semi tractors--service personnel may need to crouch or stoop in service pits, or may alternatively need to work on stepladders. When service procedures are lengthy, this can be very tiring for service personnel. This is undesirable because fatigue significantly amplifies the chance of accident. Additionally, working in crouched or extended positions for long periods of time can lead to spinal misalignment and other back injuries.